-- Copyright (C) 1996 Morgan Kaufmann Publishers, Inc

-- This file is part of VESTs (Vhdl tESTs).

-- VESTs is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at
-- your option) any later version. 

-- VESTs is distributed in the hope that it will be useful, but WITHOUT
-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-- FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-- for more details. 

-- You should have received a copy of the GNU General Public License
-- along with VESTs; if not, write to the Free Software Foundation,
-- Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

-- ---------------------------------------------------------------------
--
-- $Id: ch_14_fg_14_05.vhd,v 1.2 2001-10-26 16:29:35 paw Exp $
-- $Revision: 1.2 $
--
-- ---------------------------------------------------------------------

library ieee;  use ieee.std_logic_1164.all;

               entity master_slave_flipflop is
                 port ( phi1, phi2 : in std_logic;
                        d : in std_logic;
                        q : out std_logic );
               end entity master_slave_flipflop;


               architecture behavioral of master_slave_flipflop is

                 signal master_d : std_logic;

               begin

                 master_d <= d when phi1 = '1';

                 q <= master_d when phi2 = '1';

               end architecture behavioral;





-- code from book

               library ieee;  use ieee.std_logic_1164.all;

               entity shift_reg is
                 port ( phi1, phi2 : in std_logic;
                        serial_data_in : in std_logic;
                        parallel_data : inout std_logic_vector );
               end entity shift_reg;

--------------------------------------------------

               architecture cell_level of shift_reg is

                 alias normalized_parallel_data :
                   std_logic_vector(0 to parallel_data'length - 1)
                   is parallel_data;

                 component master_slave_flipflop is
                                                   port ( phi1, phi2 : in std_logic;
                                                          d : in std_logic;
                                                          q : out std_logic );
                 end component master_slave_flipflop;

               begin

                 reg_array : for index in normalized_parallel_data'range generate
                 begin

                   first_cell : if index = 0 generate
                   begin
                     cell : component master_slave_flipflop
                       port map ( phi1, phi2,
                                  d => serial_data_in,
                                  q => normalized_parallel_data(index) );
                   end generate first_cell;

                   other_cell : if index /= 0 generate
                   begin
                     cell : component master_slave_flipflop
                       port map ( phi1, phi2,
                                  d => normalized_parallel_data(index - 1),
                                  q => normalized_parallel_data(index) );
                   end generate other_cell;

                 end generate reg_array;

               end architecture cell_level;

-- end code from book



               library ieee;  use ieee.std_logic_1164.all;

               entity fg_14_05 is
               end entity fg_14_05;


               architecture test of fg_14_05 is

                 signal phi1, phi2, serial_data_in : std_logic := '0';
                 signal parallel_data : std_logic_vector(3 downto 0);

               begin

                 dut : entity work.shift_reg(cell_level)
                   port map ( phi1 => phi1, phi2 => phi2,
                              serial_data_in => serial_data_in,
                              parallel_data => parallel_data );

                 clock_gen : process is
                 begin
                   phi1 <= '1', '0' after 4 ns;
                   phi2 <= '1' after 5 ns, '0' after 9 ns;
                   wait for 10 ns;
                 end process clock_gen;

                 stimulus : process is
                 begin
                   serial_data_in <= '0';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '0';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '0';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '0';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '0';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '1';  wait until phi2 = '1';
                   serial_data_in <= '0';

                   wait;
                 end process stimulus;

               end architecture test;